Method of decorating surfaces



April 30, 1935. c. B. HEMMING ET AL 1,999,413

METHOD OF DECORATING SURFACES Filed Aug. 12, 1951 METAL PIGMENTED GROUNDCOAT DECALCOMANIA DECORATIO CLEAK TOP COAT CLEAR TOP COAT PIGMENTEDGROUND COAT DECALCOMANIA DECORATION I METAL BUT Z I NVEN TORS Charles B.Hemming far! Cfifman BY A TTOR Y.

Patented Apr. 30, 1935 -UNITED STATES I 1,999,413 METHOD OF DECORATINGSURFACES Charles B. Hemming, Parlin, and Earle 0. Pitman, Princeton, N.1., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del, acorporation of Delaware Application August 12, 1931, Serial No. 556,000

'7 Claims.

This invention relates to a method of decorating surfaces, and moreparticularly to a method employing the use of decalcomanias and to theproduct obtained thereby.

The present invention involves the use of the common typeofdecalcomania, in which a sheet of paper or similar material is firstcoated with a water soluble size, usually a gum, and then thedecalcomania is lithographed on the coated surface with the back side ofthe decalcomania up. This type of decalcomania is'usually applied bycoating the back side of the decalcomania with a water insoluble size,usually of the varnish type, and then applying the whole to the surfaceto be decorated when the coating has reached a tacky state. Thedecalcomania is then rolled under pressure and the surface subsequentlywashed with water to remove the paper backing and water soluble size. Asa final step, the surface is coated with a clear top coat composition toprotect the decalcomania.

A modification of this type of decalcomania is the so-called "duplexdecalcomania, in which the decalcomania is lithographed on to thin,translucent paper in place of the usual thick white paper. As thecombination is rather fragile, the whole is mounted on thicker paper bymeans of a very light coat of a gummy adhesive. This type ofdecalcomania is used in the same manner as the first type, except thatafter the decalcomania is applied to the surface to be decorated thethick sheet of 'paper is stripped off without washing, the second thinsheet being removed by washing as in the ordinary decalcomania. Thistype of decalcomania is advantageous due to the fact that the thicksheet may be waterproof, obviously impossible in the ordinarydecalcomania, and also the thin sheet may be readily removed by washing,.thus reducing the danger of damaging the design layers of delicatedecalcomanias.

There are other types of decalcomanias employing the same basicprinciples, among which may be mentioned the recently developed thinphoto film decalcomania.

All of these decalcomanias are far from satisfactory, the basicdifllculty usually being due to the fact that the design layer ofthedecalcomania itself is not anchored securely to the surface to becoated and, as a result, the detail of the design layer is likely to beblurred while being applied, and lifting and poor wearing qual-' itiesfrequently are characteristic of surfaces decorated injthis manner.

An object} of the present invention is to provide a method whereby thedecalcomania is firmly anchored to the surface to be decorated so thatthe above difficulties are avoided. Other advantages will be apparentfrom the description Hi-fiash naphtha The above objects are accomplishedaccording to the present invention by first applying to the surface tobe decorated a ground coat adapted to 'harden on application of heat,then allowing this ground coat to dry until it reaches a tacky state,then applying the decalcomania, using pressure and a somewhat elevatedtemperature. Preferably, the decalcomania is applied by means of ahydraulic press. After application of the decalcomania the surface iswashed to remove the paper or similar backing of the decalcomania andthe water soluble size, and the coated surface is then baked until hard.Subsequently, a clear top coat is applied to the decorated surface andthis is preferably also a composition adapted to harden upon theapplication of heat. If this type of clear top coat is employed, thesurface is again baked to harden the top coat.

One embodiment of the invention is illustrated in the accompanyingdrawing in which Fig. 1 shows a sectional view and Fig. 2 an elevation,with parts broken away for clarity, of a metal sheet decorated asdescribed in the example below.

The following example is given to illustrate a preferred method ofcarrying out the present invention:

Example 1.A pigmented ground coat was applied by roller coating,directly to a clean metal surface which had been scuffed, and air driedfor approximately 1 hour, at the end of which time the coat was slightlytacky. The composition of this ground coat was as follows:

. Per cent Titanium oxide 34.0 Modified polyhydrlc alcohol-polybasicacid type res n I Petroleum solventnaphtha Heavy petroleum naphthaMineral spi Modified p lyhydric alcohol-polybasic acid type resin.

Per cent Phthalic anhydride 46.30

Glycerol 21.24

Linseed oil acids 30.97

Gly l 1.49

After the specified drying period the decalcomania was applied by layingit on the slightly tacky ground coat, placing the whole on a hydraulicpress and applying a pressure of 900 pounds per square inch.

of the invention given hereinafter. the plates of the press 50' Per centPolyhydric alcohol-p'olybasic acid type resin (described above) 30.0Blown rapeseed oil 1.0 Hi-fiash naphtha 64.4 5% cobalt linoleatesolution in turpentine- 4.4 Oil of cloves 0.2

The above example gives a very specific method of carrying out thepresent invention and may be modified greatly. It has been found thatthe following represent approximately the operative limits of theprocess:-

Decalcomania, anchoring pressure 40# to 900# per sq. in. Decalcomaniaanchoring temperature C. to C. Decalcomania anchoring time .05 to 5.0minutes Ground coat and final baking temperature 60 C. to 150 C. Groundcoat and final 1 baking times 8 hours to 20 minutes It will beunderstood, however, that the invention can be carried out, and may becarried out, outside of these limits under special, circumstances. Aswill be apparent to those skilled in the art, the baking period willvary inversely with nespect to the baking temperatures given above.

It is preferred to apply the ground coat and the clear top coat byroller coating, although same may be applied by dipping, brushing,spraying, or other methods used in the art.

The method of decorating is obviously not only applicable to metal, butto many other surfaces, such as wallboard, linoleum, and similarcompositions of matter.

The type of ground coat composition used'in this method is of greatimportance and must be such that it gives a film that will harden uponapplication of heat. By this is meant that the ground coat compositionmust be such that the application of heat will cause oxidation,polymerization, condensation or similar change to give both a hard andinert film, as contrasted with compositions that merely dry throughevaporation of solvents, such as nitrocellulose lacquers. Syntheticresin compositions are particularly suitable for the ground coatcomposition, for example, polyhydric alcohol-polybasic acid glyptal typeresin compositions and compositions employing phenol-formaldehyderesins, urea-formaldehyde resins, and the like. The oil type varnishesare also suitable for this purpose, although not as preferable where ametallic surface is to be decorated, as usually a primer coat must firstbe applied to the metal to secure adequate adhesion of the oil varnish.With the synthetic resin compositions excellent adhesion is obtainedwithout the use of a primer coat. As

will be apparent to those skilled in the art, the

particular formula to be used can be widely varied. Various diluents,softeners, solvents, and pigments, and combinations thereof may be employed, the main consideration being that a composition of the hardeningtype disclosed is used.

The following formula is given to illustrate a typical 011 type varnishsuitable for use as the ground coat according to the present invention.The particular formula is well adapted for a ground coat where a walnutgrain effect is desired on a surface:

The pigments for this formula consist of Ferrite yellow dark orangeLithopone Chrome yellow medium Whit n Cosmic black Red oxide In themanufacture of this finish, the pigments are ground in the varnish base.The other ingredients specified above are added in the final mixingcycle.

The composition can be widely varied, as will be understood by thoseskilled in the art. The varnish may comprise a combination of China-woodoil and linseed oil, with or without resins, and with a wide variety ofsolvents, diluents, drlers, and pigments. v

Regardless of whether a synthetic resin type ground coat or an oilvarnish ground coat is used, the ground coat is allowed to dry untilsubstantially all of the volatile solvents therein have evaporatedbefore applying the decalcomania. In either type of ground coat a tackyfilm will be left after the volatile solvents have evaporated.

The composition of the clear top coat may be varied even more widelythan the ground coat. Any composition that will give a clear film ofsetisfactory durability may be employed, although it is preferred to usea synthetic resin composition that will harden on heating so that by afinal bake a product of great durability is obtained. However, cellulosederivative coating compositions and other coating compositions which drysimply through evaporation of the solvent constituent may be employed.Since the ground coat will have already been baked and thereby hardenedprior to application of the clear top coat and become substantiallyinsoluble in coating composition solvents, any known solvent mixture maybe used in the top coat without danger of lifting or other harmfuleffects that would result if the ground coat were subject to attack bythe solvents in the clear coat. If desired, the clear top coat may beomitted, although it is preferred to have a protective coat over thedecalcomariia.

It is believed that the greatly improved anchorage of the design layerof the decalcomania according to the present invention is due to the useof a ground coat composition adapted to harden on application of heat,and the application of the decalcomania with heat and pressure to thecoated surface. The decalcomania is forced down into the ground coat,which affords a good-anchorage while the backing of the decalcomania isremoved by washing and the subsequent baking and hardening of the groundcoat effects a lasting anchorage of unexpected strength.

The particular construction of the decalcomania forms no part of thepresent invention,

except that it is necessary to have the decalco- -mania manufacturedwith its front side in contact with the sheet of paper, or other backingused. The term decalcomania is used throughout to include only this-typeof decalcomania. The term design layer employed in the claims is used todefine the decorative layer which, together with the paper backing andsizing, forms the decalcomania. Where a duplex decalcomania of this typeis used, obviously the thick sheet of paper backing must be stripped offdry before the washing step.

The decalcomania can be applied to the tacky ground coat in a varietyofways, such as by roller, hydraulic press, etc., as long as some pressureis applied in forcing it down. It is preferred to place the article tobe decorated between the plates of a hydraulic press and then to applythe decalcomania with heat and pressure within the limits abovespecified. By this means-delicate decalcomanias can be applied withoutthe slightest blur or imperfection.

The method of the present invention may be successfully utilized in themanufacture of metal furniture, automobile dashboards and moldings, intin decorating, in the production of wall tile involving decalcomaniatransfers, linoleum desk tops, et cetera.

An important advantage of the present method over methods heretoforeknown for applying decalcomanias, is the greatly improved anchorage ofthe decalcomania to the surface to be decorated. Lifting, whichheretofore had generally been encountered in surfaces decorated withdecalcomanias is entirely eliminated. Furthermore, decalcomanias appliedaccording to the present invention are so firmly anchored that they areable to withstand severe forming operations upon the decorated surfacewithout peeling or cracking at the points under stress. This lattercharacteristic is'of great advantage in manufacturing dash boards andother metal articles which must be subjected to a forming operation.

The present method is extremely simple and easily carried out incommercial production. Surfaces such as clean scuffed auto body steel,or

ed surface until taclw, applying a decaicomania upon application ofheat", as used in the ap- 5 pended claims, is meant a composition thatwill harden and become substantially inert upon application of heat, tovarious coating composition solvents.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that we do not limit ourselves to the specific embodimentsthereof except as defined in the appended claims.

We claim:

1. Method of decorating a surface comprising applying a ground coatcomposition thereto adapted to harden upon application of heat, dryingthe coated surfaceuntil tacky, applying a decalcomania to the coatedsurface at a temperature of IO- C. and, pressure of 40-900 pounds persquare inch,'washing the surface to remove the backing and sizing of thedecalcomania, baking the coated surface until hard, and applying overthe coated surface a clear top coat.

2. Method of decorating a surface comprising applying a polyhydricalcohol-polybasic acid resin ground coat composition thereto adapted toharden upon application of heat, drying the coated surface until tacky,applying a decalcomania to the coated surface with pressure, washing thesurface to remove the backing and sizing of the decalcomania, and bakingthe coated surface until hard.

3. Method of decorating a surface comprising applying a polyhydricalcohol-polybasic acid resin ground coat composition thereto adapted toharden upon application of heat, drying the coatto the coated surfacewith heat and pressure, washing the surface to remove the backing andsizing of the decalcomania, baking the coated surface until hard, andapplying over the coated surface a clear top coat.

4. Method of decorating a surface comprising applying a polyhydricalcohol-polybasic acid resin ground coat composition thereto adapted toharden upon application of heat, drying the coated surface until tacky,applying a decalcomania to the coated surface with heat and pressure,washing the surface to remove the backing and sizing of thedecalcomania, baking the coated surface until hard, applying over thecoated surface a polyhydric alcohol-polybasic acid resin clear top coatadapted to'harden-upon application of heat, and again baking the coatedsurface to harden the top coat.

5. Method of decorating a surface comprising applying a polyhydricalcohol-polybasic acid resin ground coat composition thereto. adapted toharden upon application of heat, drying the coated surface until tacky,applying a decalc'omania to the coated surface at a temperature of70-150 C. and with a pressure of 40-900 pounds per square inch, washingthe surface to remove the backing and sizing of the decalcomania, bakingthe coated surface until hard, app yi over the coated surface apolyhydric alcohol-polybasic acid resin clear top coat adapted to hardenupon application of heat, and again baking the coated surface to hardenthe top coat.

6. An article comprisingabasehavingahard 75 baked ground coat comprisinga polyhydric alcohydric alcohol-polybasic acid resin, a design layerhol-poiybasic acid resin, a design layer over said over said groundcoat, and a hard, baked, clear ground coat, and a hard, baked, clear topcoat top coat comprising a polyhydric alcohol-polycomprising apolyhydric alcohol-polybasic acid basic acid resin applied over saiddesign layer. 5 resin applied over said design layer. 6

'7. An article comprising a sheet; of metal hav- C RLES B. HEMMING. inga hard baked ground coat comprising a poly- EARLE C. PITMAN.

